1. Field of the Invention
The present invention relates to a reservoir for aircraft, of the type containing a fluid such as oil.
Although not exclusively, reservoir according to the invention is more particularly intended to be installed in helicopters for fitting in the fluid circuit, for example the hydraulic circuit, of the helicopter.
Generally, these reservoirs are of the vented type and are provided with orifices to which in particular the fluid feed and return ducts are connected which open into the fluid contained in the reservoir close to its bottom. These ducts are moreover connected, via pumps and different fluid components, to the servo-controls and to the equipment of the helicopter.
Although such reservoirs give entire satisfaction when the helicopter is flying in usual configurations, on the other hand when it is a question of flight phases with a negative load factor, these reservoirs no longer have a maximum guarantee of operation of the fluid circuit.
Flight phases under negative load factor are temporary flight phases in which the helicopter is subjected to negative accelerations, for example when it is looping, particularly during air fights between helicopters, or when it is subjected to sudden changes of vertical level.
In the first case, since the helicopter is flying temporarily on its back, the fluid contained in the reservoir, then upturned, moves towards the top of the reservoir which corresponds at that moment to the bottom thereof. In the second case the fluid, during the sudden drop of the helicopter, tends to move towards the top of the reservoir.
Whatever the flight phase considered, there is a danger that the feed and return ducts, which open close to the bottom of the reservoir, are no longer immersed in the fluid, which may instantaneously cause draining of the pumps of the hydraulic circuit because of the inlet of air into the ducts, while generating harmful consequences.
Of course, reservoirs may be used such as those fitted on fighter aircraft whose flight phases under negative load factor are frequent and indispensable. However, such reservoirs are pressurized so that they involve a considerable additional weight, as well as a high cost, which are incompatible with helicopters.
2. Description of the Prior Art
From the document DE-C-896 598 an oil reservoir for aircraft is already known which is provided with an orifice disposed close to its bottom and in which a plate is provided separating the reservoir into a lower compartment and an upper compartment and having a passage hole between said compartments. Thus, when the aircraft dives, the movement of the oil between the lower compartment and the upper compartment is braked and said orifice remains covered with oil, so that the air cannot enter through said orifice.